ABSTRACT
Fungal sterols consist of the cyclopentanoperhydrophenanthrene tetracyclic nucleus with an equatorial 3ß-hydroxy group, a-methyl groups at C-10 and C-13 and an eight to ten carbon side chain at C-17. A concern for the functions of sterol in fungi was derived from experiments attempting to define the growth characteristics of mutants that failed to accumulate ergosterol. Generally, ergosterol auxotrophs have genetic defects resulting in biochemical losses early in the sterol biosynthetic pathway. Since ergosterol is a metabolically expensive molecule for the organism to synthesize, we assume that the esterification of ergosterol during growth retardation conserves the sterol for reuse during active growth. Transmethylation at C-24 is characteristic of fungal and plant sterol biosynthesis. The specific sterol that had been fed to the yeast showed patterns of anisotropy that were similar to that of membrane preparations, having no discontinuities. Understanding the various roles of sterol is not only an intellectually challenging and exciting exercise, but it has important practical ramifications also.
